Online Electronics and Communication Engineering Test - Previous Exam Papers Test 1

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Total number of questions: 20.
Time allotted: 30 minutes.
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As the temperature increases the mobility of electrons __________ .

decreases because the number of carries increases with increased collisions

increases because the number of carries decreases with decreased collisions

remains same

none of the above

[#]

For the power amplifier circuit shown below, the maximum power dissipated by both output transistor is

9.66 W

30.11 W

31.66 W

33.66 W

[#]

A periodic rectangular signal, x(t) has the waveform shown in the given figure. Frequency of the fifth harmonic of its spectrum is __________

200 Hz

250 Hz

400 Hz

1250 Hz

[#]

In the following limiter circuit, an input voltage V₁ = 10 sin 100pt applied. Assume that the diode drop is 0.7 V when it is forward biased. The zener breakdown voltage is 6.8 V

The maximum and minimum values of the output voltage respectively are

6.1 V, -0.7 V

0.7 V, -7.5 V

7.5 V, -0.7 V

7.5 V, -7.5 V

[#]

A 300 MHz plane EM wave is propagating in free space. The wave is incident normally on an infinite copper slap. The antenuation constant for the wave is (σ_copper = 5.8 x 10⁷ mho/ m). The skin depth is

0.005 x 10^-3 m

0.0038 x 10^-3m

0.0028 x 10^-3 m

0.0024 x 10^-3 m

[#]

Find the value of i_x if each resistance is of 3 Ω and each battery is of 6 V.

1.1428 V

1.432 A

0.2892 A

O A

[#]

The Z inverse of the given Z transform is :

unit step

unit impulse

unit ramp

unit parabola

[#]

The probability density function (PDF) of a random variable X is as shown below

The corresponding cumulative distribution function (CDF) has the form

[#]

Consider the program segment written for 8085 based system:
LXI S, FFFFH
MVI A, 00H
MVI B, 0FH
SUB B
CNC GOLOC
MVI A, FFH
where in the program subroutine labelled ''GOLOC'' introduces delay of 28 T-states only. How many T-states are required to execute above program statement?

Indeterminate

[#]

10.

The magnitude plot of a composite signal x(t) = e^3jt + e^4jt is __________ .

Half wave rectified sinusoid

Full wave rectified sinusoid

Exponentially increasing sinusoid

Exponentially decreasing sinusoid

[#]

11.

In the given figure

.
The damped frequency is __________ .

0 rad/sec

2 rad/sec

3/2 rad/sec

None of these

[#]

12.

The driving point impedance of the following network is given by

. The component values are

L = 5H, R = 0.5Ω, C = 0.1F

L = 0.1H, R = 0.5Ω, C = 5F

L = 5H, R = 2Ω, C = 0.1F

L = 0.1H, R = 2Ω, C = 5F

[#]

13.

The Table given below is the mark obtained by 2 students in 8 different subjects.

The regression line of y on x is:

y + 0.57x = 9.7558

y - 0.57x = 9.758

033y + x = 6.335

0.33y - x = 6.335

[#]

14.

A matched filter has a frequency response given:

The impulse response h(t) of the filter is :

[δ(t) - δ(t - T]

[u(t) - u(t - T)]

[S gn(t) - Sgn(t - t)]

[S gn(t) + Sgn(t - T)]

[#]

15.

Value of 'K' for the system for which the system is stable:

K < 1

K > 1

K < 2

K > 2

[#]

16.

A 3 x 8 decoder with two enable inputs is to be used to address 8 blocks of memory. What will be the size of each memory block when addressed from a sixteen bit bus with two MSBs used to enable the decoder?

2 K

4 K

16 K

64 K

[#]

17.

The circuit shown in the figure is used to charge the capacitor C alternately from two current sources as indicated. The switches S₁ and S₂ are mechanically coupled and connected as follow
For 2nT ≤ t < (2n + 1)T, (n = 0, 1, 2, ...) S₁ to P₁ and S₂ to P₂
For (2n + 1) T ≤ t < (2n + 2)T, (n = 0, 1, 2, ...) S₁ to Q₁ and S₂ to Q₂
Assume that the capacitor has zero initial charge. Given that u(t) is a unit step function, the voltage Vc(t) across the capacitor is given be

(- 1)ⁿ tu(t - nT)

u(t) + 2

(-1)ⁿ u(t - nT)

tu(t) + 2

(-1)ⁿ (t - nT) u(t - nT)

[0.5 - e^{-(t - 2nT)} + 0.5e^{-(t - 2nT - T)} ]

[#]

18.

The following properties are associated with ferroelectric materials:

Its susceptibility is negative.
The susceptibility is expressed as
where c is the Curie constant and T_c is the Curie temperature.
It has permanent dipoles oriented randomly.

Which of the above statements is/are correct?

1 only

1 and 3

2 only

1, 2 and 3

[#]

19.

Consider the network: Impedance of this network as a function of the complex frequency is consists of a certain number of zeros and poles. What is the location of poles?

-2

-2, ∞

2, ∞

[#]

20.

Assertion (A): The line integral of B about a closed contour, in a region containing steady current, is μ₀ times the total net current, following through the contour of integration.

Reason (R): The curl of B is equal to μ₀ times the current density vector J

Both (A) and (R) are true and (R) is the correct explanation of (A)

Both (A) and (R) are true but (R) is not the correct explanation of (A)

(A) is true but (R) is false

(A) is false but (R) is true

[#]

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